Construction of scanning or imaging arrays suitable for large documents

Abstract

Semiconductor chips, such as photosensor arrays in a full-width scanner, are mounted on printed wiring boards. The printed wiring boards are in turn mounted on a second layer of printed wiring board material. The two layers of printed wiring board material are attached so that the seams between adjacent printed wiring boards in each layer alternate in a brick-like fashion. This structure enables arrays of semiconductor chips to be constructed in relatively long lengths, with minimal risk of damage caused by thermal stresses.

What is claimed is:  
     
       1. An imaging apparatus, comprising: 
       a first printed wiring board and a second printed wiring board, arranged whereby an edge of the first printed wiring board is adjacent an edge of the second printed wiring board, creating a seam therebetween, the first printed wiring board and second printed wiring board each defining a first main surface and a second main surface;  
       a set of semiconductor chips attached to the first main surface of each of the first wiring board and second wiring board; and  
       at least a portion of the second main surface of each of the first wiring board and second wiring board being attached to a second-layer board, whereby the seam between the first printed wiring board and the second printed wiring board is spaced from an edge of the second-layer printed wiring board.  
     
     
       2. The apparatus of claim  1 , further comprising conductors disposed on the first main surface of each of the first wiring board and second wiring board. 
     
     
       3. The apparatus of claim  1 , wherein the first and second printed wiring board and the second-layer board, have a substantially equal thermal coefficient of expansion. 
     
     
       4. The apparatus of claim  1 , wherein the first and second printed wiring board and the second-layer board all substantially comprise an identical material. 
     
     
       5. The apparatus of claim  1 , wherein the first and second printed wiring board, and the second-layer board all substantially comprise a ceramic. 
     
     
       6. The apparatus of claim  1 , wherein the first and second printed wiring board, and the second-layer board all substantially comprise alumina. 
     
     
       7. The apparatus of claim  1 , the semiconductor chips including photosensors. 
     
     
       8. The apparatus of claim  1 , the semiconductor chips including light-emitting diodes. 
     
     
       9. The apparatus of claim  1 , the semiconductor chips including a plurality of at least a portion of ink-jet ejectors. 
     
     
       10. The apparatus of claim  1 , wherein the semiconductor chips are spaced apart from each other by a predetermined distance. 
     
     
       11. The apparatus of claim  1 , wherein the edge of the first printed wiring board and the edge of the second printed wiring board are in contact. 
     
     
       12. The apparatus of claim  1 , further comprising a second second-layer board, the second second-layer board including an edge abutting an edge of the first-mentioned second-layer board, and the second second-layer board being attached to the second main surface of the second printed wiring board.